/*
 * Copyright (c) 2004-2022, University of Oslo
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors 
 * may be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.hisp.dhis.commons.util;

/**
 * @author Stian Sandvold
 */
public class CronUtils {
  public enum Weekday {
    SUNDAY("SUN"),
    MONDAY("MON"),
    TUESDAY("TUE"),
    WEDNESDAY("WED"),
    THURSDAY("THU"),
    FRIDAY("FRI"),
    SATURDAY("SAT");

    private final String name;

    Weekday(String name) {
      this.name = name;
    }
  }

  /**
   * Generates a cron pattern that will execute every day at the given hour:minute
   *
   * @param minutes
   * @param hours
   * @return a cron pattern
   */
  public static String getDailyCronExpression(int minutes, int hours) {
    return getCronExpression(
        "0", String.valueOf(minutes), String.valueOf(hours), "*/1", null, null);
  }

  /**
   * Generates a cron pattern that will execute every week at the dayOfWeek at hour:minute
   *
   * @param minutes
   * @param hours
   * @param dayOfWeek can be 0-7. 0 and 7 both resolve to sunday
   * @return a cron pattern
   */
  public static String getWeeklyCronExpression(int minutes, int hours, int dayOfWeek) {
    return getCronExpression(
        "0",
        String.valueOf(minutes),
        String.valueOf(hours),
        null,
        null,
        Weekday.values()[(dayOfWeek % 7)]
            .name // both 0 and 7 are valid as Sunday in crontab patterns
        );
  }

  /**
   * Generates a cron pattern that will execute every month at the dayOfMonth at hour:minute
   *
   * @param minutes
   * @param hours
   * @param dayOfMonth
   * @return a cron pattern
   */
  public static String getMonthlyCronExpression(int minutes, int hours, int dayOfMonth) {
    return getCronExpression(
        "0",
        String.valueOf(minutes),
        String.valueOf(hours),
        String.valueOf(dayOfMonth),
        "*/1",
        null);
  }

  /**
   * Joins together each segment of a cron pattern into a complete cron pattern.
   *
   * @param seconds a valid cron segment
   * @param minutes a valid cron segment
   * @param hours a valid cron segment
   * @param days a valid cron segment
   * @param months a valid cron segment
   * @param weekday a valid cron segment (MON-SUN)
   * @return a cron pattern
   */
  public static String getCronExpression(
      String seconds, String minutes, String hours, String days, String months, String weekday) {
    return String.join(
        " ",
        (seconds == null ? "*" : seconds),
        (minutes == null ? "*" : minutes),
        (hours == null ? "*" : hours),
        (days == null ? "*" : days),
        (months == null ? "*" : months),
        (weekday == null ? "*" : weekday));
  }
}
